Premixer assembly for gas turbine combustor

ABSTRACT

A novel and improved combustion liner for use in a gas turbine engine is provided in which the premixer assembly is removably fastened to the combustion liner. Apparatus and method for removably securing the premixer assembly to the combustion liner is provided. A combustor dome plate, swirler assembly and inlet ring basket are coupled together by a plurality of removable fasteners in order to increase accessibility to portions of the combustion liner for inspection and repair processes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application Ser. No. 61/815,835, filed on Apr. 25, 2013. This application is related by subject matter to commonly-assigned U.S. Non-Provisional Patent Applications entitled REMOVABLE SWIRLER ASSEMBLY FOR A COMBUSTION LINER (Attorney Docket No. PSM-316/PSSF.199280) and SWIRLER ASSEMBLY AND STIFFENING MECHANISM FOR PREMIXER ASSEMBLY OF A GAS TURBINE COMBUSTOR (Attorney Docket No. PSM-318/PSSF.199282) and assigned to the same assignee as the present application.

TECHNICAL FIELD

The present invention generally relates to a gas turbine combustor. More specifically, the present invention is directed towards a premixer assembly for a gas turbine combustor, where the premixer assembly is secured together by a plurality of removable fasteners. As a result, the premixer assembly enhances combustor performance and increases component life through improved assembly and disassembly techniques and improved cooling configurations.

BACKGROUND OF THE INVENTION

In a typical gas turbine engine, a compressor having alternating stages of rotating and stationary airfoils is coupled to a turbine through an axial shaft, with the turbine also having alternating stages of rotating and stationary airfoils. The compressor stages decrease in size in order to compress the air passing therethrough. The compressed air is then supplied to one or more combustors, which mixes the air with fuel. An ignition source proximate the one or more combustors ignite the mixture, forming hot combustion gases. The expansion of the hot combustion gases drives the stages of a turbine, which is coupled to the compressor through an axial shaft. The exhaust gases can then be used as a source of propulsion, to generate steam through a heat recovery steam generator, or in powerplant operations to turn a shaft coupled to a generator for producing electricity.

The combustion system of a gas turbine engine can take on a variety of configurations. A combustion system for a gas turbine engine can comprise a single combustion chamber, a plurality of individual combustion chambers spaced about the axis of the engine, a plenum-type combustion system, or a variety of other combustion systems. Depending on the engine geometry, performance requirements, and physical operating location, the exact combustor arrangement will vary.

One such combustion system comprises a casing secured to the frame of the engine, a combustion liner secured within at least a part of the casing, and one or more fuel nozzles positioned within or adjacent to the combustion liner for injecting a fuel (gas, liquid, or both) into the combustion chamber. The combustion system is in fluid communication with the engine. More specifically, the casing and liner arrangement provides a way for air from the compressor to enter the combustion system, where it mixes with fuel from the one or more fuel nozzles. The fuel-air mixture is ignited by an ignition source, such as a spark igniter. Hot combustion gases travel through the combustion liner and often through one or more transition pieces and into the turbine. The transition piece is essentially a duct having a geometry that changes from the shape of the combustor to the inlet of the turbine.

The combustion liner is at the center of combustor operations. The combustion liner geometry is dictated by a variety of factors including the operating parameters of the engine, performance requirements, and available geometry. While combustion liner geometries can vary, the combustion liner typically includes at least a portion for receiving fuel nozzles, for mixing fuel and air together and for containing the reaction when the fuel and air mixture is ignited.

Combustion liners of the prior art have met certain performance requirements, but have also exhibited various shortcomings. For example, prior combustion liners have been primarily or exclusively welded assemblies, thereby making it difficult for operators or repair facilities to easily access all of the features of the combustion liner to be repaired. Furthermore, prior combustor designs of similar structure were capable of operating approximately 8,000 hours prior to refurbishment or replacement. In an effort to improve gas turbine engine availability, there is a strong desire in the operator community to be able to extend the timeframe between repairs, so as to reduce engine downtime and repair/overhaul costs.

SUMMARY

In accordance with the present invention, there is provided a novel and improved combustion liner for use in a gas turbine engine. The combustion liner is generally cylindrical in shape and has an inlet end and a discharge end, opposite the inlet end. The combustion liner of the present invention further comprises a premixer assembly which is removably fastened to the combustion liner.

In accordance with an embodiment of the present invention, there is provided a premixer assembly for a gas turbine combustor comprising an inlet ring basket, a plurality of swirler assemblies each having a premix tube, premix swirler in the premix tube, and a first and second mounting block positioned along the premix tube, a dome plate and a plurality of fasteners, where lugs of the inlet ring basket are positioned between a mounting block of the swirler assembly and the dome plate such that the fasteners pass through the dome plate, openings in the lugs and a hole of the mounting block so as to assemble the premixer.

In accordance with another embodiment of the present invention, a method of assembling a premixer for a gas turbine combustor is disclosed. A dome plate is provided having a plurality of dome mounting holes, an inlet ring basket having a plurality of lugs, and a plurality of swirler assemblies, each having at least one mounting block and hole therein. The swirler assemblies are then inserted into the inlet ring basket and loosely retained in the radial direction by the first mounting block. The dome plate is then placed into contact with the plurality of lugs and the swirler assemblies are then inserted into the dome plate. The mounting holes of the dome plate are aligned with corresponding openings in the lugs and holes in the mounting block. A removable fastener is then placed through the fastener opening of the dome plate, the opening in the lug, and the hole in the mounting block so as to secure the dome plate, lug (inlet ring basket) and mounting block (swirler assembly) together.

In accordance with yet another embodiment of the present invention, an interface joint for coupling components of a premixer assembly is disclosed. The interface joint comprises a lug of an inlet ring basket, a swirler assembly having a mounting block positioned along an outer wall of the premix tube of the swirler assembly, and a dome plate. One or more fasteners secure the lug, mounting block, and dome plate together.

Additional advantages and features of the present invention will be set forth in part in a description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned from practice of the invention. The instant invention will now be described with particular reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The present invention is described in detail below with reference to the attached drawing figures, wherein:

FIG. 1 is a partial cross section view of a gas turbine engine of the prior art in which a combustion system in accordance with an embodiment of the present invention is capable of being used;

FIG. 2 is a cross section view of a gas turbine combustor of the prior art capable of operating within the gas turbine engine of FIG. 1;

FIG. 3 is a perspective view of a combustion liner in accordance with an embodiment of the present invention;

FIG. 4 is a cross section view of a combustion liner taken through a pilot swirler in accordance with an embodiment of the present invention;

FIG. 5 is an alternate view of the cross section of FIG. 4, in accordance with an embodiment of the present invention;

FIG. 6 is a cross section view of a combustion liner taken through the main swirler in accordance with an embodiment of the present invention;

FIG. 7 is an alternate view of the cross section of FIG. 6, in accordance with an embodiment of the present invention;

FIG. 8 is a perspective view of a main swirler portion of the combustion liner of FIG. 3 in accordance with an embodiment of the present invention;

FIG. 9 is a detailed cross section view taken through the inlet portion of the combustion liner of FIG. 3 in accordance with an embodiment of the present invention;

FIG. 10 is a partial cross section view of the main swirler portion of the combustion liner in accordance with an embodiment of the present invention;

FIG. 11 is a detailed section view of the interface joint for the premixer assembly in accordance with an embodiment of the present invention; and,

FIG. 12 is a flow diagram of the steps for assembling a premixer for a gas turbine combustor.

DETAILED DESCRIPTION

The subject matter of the present invention is described with specificity herein to meet statutory requirements. However, the description itself is not intended to limit the scope of this patent. Rather, the inventors have contemplated that the claimed subject matter might also be embodied in other ways, to include different components, combinations of components, steps, or combinations of steps similar to the ones described in this document, in conjunction with other present or future technologies.

Referring initially to FIG. 1, a gas turbine engine 100 of the prior art is depicted in partial cross section. The gas turbine engine 100 generally comprises an outer casing 102, enveloping the main portions of the engine. A shaft 104 extends axially along an engine axis A-A and is coupled to a compressor 106 and a turbine 108. The compressor 106 receives air through inlet region 110 and directs the air through alternating rows of rotating and stationary airfoils of decreasing size in order to compress the air as it passes therethrough, thereby increasing the temperature and pressure of the air. The compressed air is then directed through one or more combustion systems 112 where fuel and air are mixed together and ignited to form hot combustion gases. The hot combustion gases are then directed into the turbine 108 and through alternating rows of rotating and stationary airfoils of increasing size, so as to expand the fluid and convert the energy of the combustion gases into mechanical work to drive the shaft 104. The shaft 104 may also be coupled to a shaft of an electrical generator for purposes of generating electricity (not shown).

FIG. 2 discloses a cross section of a combustor 200 of a gas turbine engine of the prior art. As such, this typical gas turbine combustor 200 comprises a casing 202, a cover 204, one or more fuel injectors 206, and a combustion liner 208. A transition piece 210 connects the combustion liner 208 to an inlet of the turbine 212.

The present invention is shown in detail in FIGS. 3-12 and discloses a new and improved premixer assembly for a combustion liner of a gas turbine engine. Referring initially to FIGS. 3-7, a combustion liner 300 having a premixer assembly 330 is disclosed. The combustion liner 300 comprises a generally cylindrical liner body 302 having an inlet end 304, an outlet, or discharge end 306, and an axis B-B extending through the combustor. The combustion liner 300 is generally cylindrical in cross section, but it is understood that the combustion liner 300 can vary in shape, have tapered sections, or sections of varying diameter. The combustion liner 300 is generally fabricated from rolled sheet metal that is welded along an axial seam and can be formed or expanded into a modified cylindrical structure depending on the specific combustion geometry. The combustion liner 300 is preferably manufactured from a high temperature alloy, such as Haynes 230, capable of withstanding elevated combustor conditions upwards of approximately 1400 degrees Fahrenheit. Alternate materials can be used such as Hastelloy-X or Inconel.

The combustion liner 300 further comprises an inlet ring basket 308 secured to the generally cylindrical body 302. The inlet ring basket 308, as depicted in FIG. 3-7, consists of a series of generally axially-oriented spindles 310 coupled to a forward ring 312 and extends forward from the inlet end 304 of the combustion liner 300. The forward ring 312 is positioned a distance from the combustion liner 300 in order to establish a mating location for a set of fuel nozzles (not shown) in order to position the fuel nozzles in the proper axial position within the combustor.

Referring now to FIGS. 9 and 10, the inlet ring basket 308 also comprises a plurality of lugs 309 located in an annular array about the inlet ring basket 308, with each of the lugs 309 having an opening 309A extending through the lug 309. The lugs 309 extend radially inward from the inlet ring basket 308 and are used in part for securing a premixer assembly 330, as discussed in more detail below. The lugs 309 can be fabricated separately and welded to the inlet ring basket 308 or cast as part of the inlet ring basket 308. The plurality of lugs 309 can be a fabricated component or a casting and is preferably made from a stainless steel material.

More specific details of the present invention are shown in FIGS. 6-8, 10 and 11. In addition to the inlet ring basket 308 discussed above, the premixer assembly 330 also comprises a plurality of swirler assemblies 332, each swirler assembly 332 for receiving a fuel injector. The swirler assembly 332 comprises a premix tube 342 having an inlet end 342A and an opposing outlet end 342B, and a longitudinal axis C-C extending therethrough. The swirler assembly 332 also comprises a premix swirler 336 positioned within the premix tube 342 where the premix swirler 336 has a plurality of turning vanes 338 for imparting a swirl to a passing flow through the premix tube 342. For the embodiment depicted in FIGS. 8-10, the premix tube 342 is slightly conical, however, alternate shapes for the premix tube 342 are possible.

The swirler assembly 332 also comprises two mounting blocks for securing the swirler assembly in a gas turbine combustor. A first mounting block 344 is positioned along an outer wall of the premix tube 342 proximate the inlet end 342A of the premix tube 342. The first mounting block 344 includes a plurality of first holes 348 located in an outer face 347 and oriented generally perpendicular to the longitudinal axis C-C of the premix tube 342, as shown in FIG. 8.

The swirler assembly 332 also comprises a second mounting block 346 positioned along the outer wall of the premix tube 342 and spaced an axial distance from the first mounting block 344. The second mounting block 346 also has one or more second holes 356 extending through the second mounting block 346 in a direction generally perpendicular to the plurality of first holes 348.

A plurality of fasteners 350 and 358 are used to secure the swirler assemblies 332 to the inlet basket 308. Fasteners 350 are used to secure the swirler assemblies 332 to the inlet basket 308 via the first mounting block 344 where the fasteners 350 are oriented generally perpendicular to the longitudinal axis C-C of the swirler assemblies 332. Fasteners 358 are used to secure the swirler assemblies 332 to the inlet basket 308 via the second mounting block 346 where the fasteners 358 are oriented generally parallel to the longitudinal axis C-C of the swirler assemblies 332.

The premixer assembly 330 also comprises a dome plate 334 spaced an axial distance from the second mounting block 346 of each of the swirler assemblies 332. As shown in FIGS. 9-11, the dome plate 334 is oriented generally parallel to the second mounting block 346 and the plurality of lugs 309. The dome plate 334 is positioned against a face of the lugs 309. The dome plate 334, which can be more clearly seen in FIGS. 10 and 11, is a generally cylindrical plate fabricated from a stainless steel. The exact thickness of the plate can vary, but is approximately 0.350 inches thick. The dome plate 334 also comprises a large opening 370 for each swirler assembly 332 to pass therethrough, a series of fastener openings 372 for each axial fastener 358 to pass through, and a plurality of cooling holes 374. The dome plate 334 includes numerous cooling holes 374 for directing a flow of compressed air into the combustion zone of the combustion liner 300. For the dome plate 334 shown in FIGS. 10 and 11, the cooling holes 374 are oriented generally perpendicular to the dome plate 334 (the cooling holes 374 are generally parallel to the longitudinal axis C-C of the swirler assemblies 332). Alternatively, the cooling holes 374 could be oriented at a surface angle relative to the dome plate 334 as well as a compound angle in order to impart a swirl to the air passing through the dome plate 334 or to improve the cooling effectiveness through the dome plate 334. The exact quantity, size, and shape of the cooling holes 374 can vary depending on the amount of compressed air to be directed through the dome plate 334 as well as to maintain a desired pressure drop into the combustion zone.

Referring to FIG. 11, the plurality of lugs 309 of the inlet ring basket 308 are positioned axially between the mounting blocks 346 of the swirler assemblies 332 and the dome plate 334. A plurality of fasteners 358 pass through each of the fastener openings 372 in the dome plate 334, through the openings 309A in the lugs 309 and through a second hole 356 in the second mounting block 346.

The main swirler assemblies 332 are positioned so as to be in fluid communication with adjacent tubes 352, or hoovers, which pass the flow of fuel and air from the main swirler assembly 332 to the mixing zone of the combustion liner 300. That is, the main swirler assemblies 332 are positioned so as to be adjacent to or slightly engaged in the tubes 352. In order to ensure that the main swirler assemblies 332 are in the proper radial position in the combustion liner and dome plate 334 and thereby maintain a desired radial clearance with the tubes 352, a plurality of stand offs 354 are located about the outer surface of the premix tubes 342.

The present invention also provides an interface joint for coupling components of a premixer assembly 330. Referring to FIG. 11, the interface joint 400 comprises a lug 309 of an inlet ring basket 308, where the lug 309 has an opening 309A extending through the thickness of the lug 309. The interface joint 400 also includes a swirler assembly 332 having a premix tube 342, a premix swirler 336 and a mounting block 346 having one or more holes 356 extending through the mounting block 346 in a direction parallel to the premix tube 342. A dome plate 334 also forms part of the interface joint 400. More specifically, the dome plate 334, has a plurality of cooling holes 374, fastener openings 372, and larger opening 370 for receiving the swirler assemblies 332, as discussed above. The interface joint 400 also includes one or more removable fasteners 358 for securing the lug 309, mounting block 346, and dome plate 334 together. The fastener 358 draws the mounting block 346 and dome plate 334 towards the lug 309 of the inlet ring basket 308.

Referring now to FIG. 12, the present invention also provides a method 1200 of assembling a premixer for the gas turbine combustor. The method comprises the step 1202 of providing the components of the premixer including a dome plate having a plurality of fastener openings, an inlet ring basket having a plurality of lugs where each lug has an opening extending therethrough, and a plurality of swirler assemblies having mounting blocks with holes contained therein.

In a step 1204, the swirler assemblies are inserted into the inlet ring basket and loosely affixed to the first mounting block. Then, in a step 1206, the dome plate is placed in contact with the plurality of lugs of the inlet ring basket and in a step 1208, the swirler assemblies are inserted into the cup openings, or large openings, of the dome plate 334. Then, in a step 1210, the fastener opening in the dome plate, the opening in the lug, and the opening in the mounting block of the swirler assembly are all aligned together. For the embodiment shown in FIGS. 10 and 11, the swirler assembly has two mounting blocks, and for this embodiment, it is the second, or aft-most mounting block that is used this assembly process.

Once the holes of the three components to be secured together are aligned, in a step 1212, a removable fastener is placed through the fastener opening in the dome plate, through the opening in the lug, and through the hole in the mounting block, as shown in FIG. 11. The removable fastener engages a series of threads in the hole of the mounting block so as to secure the dome plate, lug, and mounting block of a swirler assembly together. This process is repeated for each of the fastener openings in the dome plate, corresponding lugs and swirler assemblies such that the dome plate and swirler assemblies are then bolted to the inlet ring basket.

The present invention has been described in relation to particular embodiments, which are intended in all respects to be illustrative rather than restrictive. Alternative embodiments and required operations, such as machining of shroud faces other than the hardface surfaces and operation-induced wear of the hardfaces, will become apparent to those of ordinary skill in the art to which the present invention pertains without departing from its scope.

From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects set forth above, together with other advantages which are obvious and inherent to the system and method. It will be understood that certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and within the scope of the claims. 

1. A premixer assembly for a gas turbine combustor comprising: an inlet ring basket having a plurality of lugs, with each of the lugs having an opening extending therethrough; a plurality of swirler assemblies each for receiving a fuel injector, the swirler assemblies each comprising: a premix tube having an inlet end, an opposing outlet end and a longitudinal axis extending therethrough; a premix swirler positioned within the premix tube, the swirler having a plurality of turning vanes for imparting a swirl to a passing flow; a first mounting block positioned along an outer wall of the premix tube proximate the inlet end and having a plurality of first holes oriented generally perpendicular to the longitudinal axis; and, a second mounting block positioned along the outer wall of the premix tube a distance from the first mounting block, the second mounting block has one or more second holes extending through the second mounting block in a direction generally perpendicular to the plurality of first holes; a dome plate spaced an axial distance from the second mounting block of each of the swirler assemblies, and oriented generally parallel to the second mounting block, the dome plate having a plurality of cooling holes; and, a plurality of fasteners; wherein the plurality of lugs are positioned axially between the second mounting blocks of the swirler assemblies and the dome plate and the plurality of fasteners pass through the dome plate, the openings in the lugs and the one or more second holes of the second mounting blocks.
 2. The premixer assembly of claim 1, wherein the plurality of lugs are integrally formed with the inlet ring basket.
 3. The premixer assembly of claim 1, wherein each of the one or more second holes corresponds to one of the plurality of lugs and openings.
 4. The premixer assembly of claim 1, wherein each of the swirler assemblies is secured to the inlet basket by a plurality of fasteners.
 5. The premixer assembly of claim 4, wherein the plurality of fasteners securing the swirler assemblies to the inlet ring basket are oriented both parallel to and perpendicular to the longitudinal axis of the premix tube of the swirler assemblies.
 6. The premixer assembly of claim 1, wherein the holes in the dome plate are oriented parallel to the longitudinal axis of the premix tube.
 7. The premixer assembly of claim 1, wherein the holes in the dome plate are oriented at an angle relative to the longitudinal axis of the premix tube.
 8. The premixer assembly of claim 1, further comprising a plurality of stand-offs positioned along the premix tube adjacent the outlet end.
 9. A method of assembling a premixer for a gas turbine combustor comprising: providing a dome plate having a plurality of fastener openings, an inlet ring basket having a plurality of lugs, each lug having an opening extending therethrough, and a plurality of swirler assemblies, the swirler assemblies each having a first and second mounting block, with the first mounting block having a plurality of first holes and the second mounting block having one or more second holes; inserting the plurality of swirler assemblies into the inlet ring basket; placing the dome plate in contact with the plurality of lugs of the inlet ring basket; inserting the swirler assemblies into corresponding cup openings in the dome plate. aligning a fastener opening of the dome plate with the opening of a lug and a second hole of the second mounting block; placing a removable fastener through the fastener opening of the dome plate, the opening of the lug and the second hole of the second mounting block so as to secure the dome plate, lug and second mounting block together.
 10. The method of claim 9, wherein the plurality of dome mounting holes are located in an annular array about a perimeter of the dome plate.
 11. The method of claim 10, wherein the dome plate further comprises a plurality of cooling holes.
 12. The method of claim 9, wherein the plurality of lugs are positioned between the dome plate and the second mounting blocks of the swirler assemblies.
 13. The method of claim 9, wherein the one or more second holes in the second mounting block is threaded.
 14. The method of claim 9, wherein the swirler assemblies are inserted into the corresponding cup openings such that the second mounting blocks are in contact with the lugs of the inlet ring basket.
 15. The method of claim 14, wherein the swirler assemblies are inserted in the corresponding cup openings such that a plurality of stand-offs positioned along an outer surface of the premix tube contact the dome plate.
 16. The method of claim 9, wherein a tightening of the removable fastener draws the second mounting block and the dome plate toward the lug of the inlet ring basket.
 17. An interface joint for coupling components of a premixer assembly comprising: an inlet ring basket having a lug where the lug has an opening extending therethrough; a swirler assembly having a premix tube, a premix swirler positioned within the premix tube, and a mounting block positioned along an outer wall of the premix tube and having one or more holes extending through the mounting block in a direction parallel to the premix tube; a dome plate having a plurality of cooling holes; and, one or more fasteners for securing the lug, mounting block and dome plate together.
 18. The interface joint of claim 17, wherein the inlet ring basket has a plurality of lugs located in an annular array about the inlet ring basket.
 19. The interface joint of claim 17, wherein the plurality of fasteners are removable.
 20. The interface joint of claim 17, wherein the fasteners draw the mounting block and the dome plate towards the lug of the inlet ring basket. 